A neutron detector was required for an area of our research. After
considering several different alternatives, including BF3 (boron triflouride) and plastic scintillators,
it was decided to use a 3He (helium 3, an isotope of helium) detector with a HDPE moderator. After acquiring
the detector tube, we built a custom power supply and amplifier into a housing
that once held a RF power meter detector. Below are photos and descriptions
of this project.

Above is the 3He tube mounted to a N connector that will mate with the connector on the repurposed power meter.

Above are the parts salvaged from the power meter head, including the LEMO connector with its original insert removed.

Above
are the printed circuit board and the chrome mask used to expose the photo
resist. The mask was generated on our custom mask making machine.

Above, the PCB with components mounted is shown.

Above, the original LEMO connector with guts removed and the replacement LEMO connector that was inserted in the original shell.

Above is the assembled amplifier and 3He detector tube with the outer covers shown.

Above, the bottom of the amplifier assembly is shown, including the high voltage power supply.

The final assembly with covers in place and the HPDE moderator shown next to the 3He tube.

Above
is a oscilloscope plot showing a neutron detection event. The green
trace is used as a trigger and the yellow one is the output of the amplifier
(the length of the output pulse has been streached to match our application).